Need advice...Falling out of love with my husband.

I'll try to make this short and sweet, my husband is bipolar, he does take meds. Usually I can manage. But recently everything he does gets on my last nerve, we constantly argue, the sex is awful, I literally have dreams of me cheating on him. I know I love him, but I feel like I'm falling out of love we have been together for almost 6 years and married for 2. We have a 3 month old daughter and I know we have to give this a fair shot. But how can I fall back in love with him. And BTW the day my daughter was born he admitted to cheating on me.... not with anyone particular but he PAID a woman to stick it in her ass. Because that's my only no no. I guess I'm just asking for opinions here.